The present invention relates to shadow suppression in ultrasound imaging.
Ultrasound shadowing is caused by poor transmission of acoustic energy through or high reflection from scattering objects. For example, dense tissue may cause a shadow obscuring return from tissue separated from the transducer by the dense tissue. As another example, shadowing occurs due to poor transducer contact. The shadows themselves appear as areas of low echogenicity that are typically highly correlated with the direction of transmission.
Shadows may occur in various modes of imaging, such as occurring in steered spatial compounding. One component frame of data is acquired by scanning along scan lines at one angle relative to a transducer. A second component frame of data is acquired by scanning along scan lines at a different angle. The frames of detected data are compounded together and displayed as an image. When imaging using steered spatial compounding, shadows create fork-like image artifacts since the shadows tend to weigh down the compounded image mean in the shadowing locations. Anatomy information may be lost due to this reduction. For reducing shadowing in steered spatial compounding, differences between steered spatial component images may be used to identify shadows. However, proper spatial image registration may not be achieved, resulting in poor shadow identification.